Increasingly, user equipment (UE) include multiple radio transceivers to access various networks and services ubiquitously. As shown in FIG. 1, a transceiver module 100 is capable of including multiple transceivers in a UE which may include co-located transceivers for employing long term evolution (LTE) 110, global navigation satellite system (GNSS) 120, and Bluetooth™ (BT)/WiFi™ radio 130 access technologies (RATs). FIG. 1 is but one example of co-located RATs in a UE other configurations are possible which may include more or less co-located transceivers as well as deploying other RATs. (for example a Zigbee transceiver). Due to the extreme proximity of the transceivers and the fact that each radio technology is capable of operating on the same frequency bands each transceiver may interfere with the transmitting and receiving of another transceiver within the same UE. Some non-limiting examples of frequencies bands capable of being used by multiple RATs are the Industrial, Scientific and Medical (ISM) on bands of 2400˜2483.5 MHz or the so-called “TV White Space” recently designated as unlicensed spectrum in the United States on bands of 300 MHz to 400 MHz. For example, an LTE transceiver 110 operates at Band 40 (2300˜2400 MHz) in time division duplex (TDD) Mode and Band 7 uplink (UL) (2500-2570 MHz) operates in frequency division duplex (FDD) Mode. While on the same frequency spectrum, a BT transceiver 130 operates seventy-nine (79) channels of 1 MHz each in the ISM band in the range of 2402˜2480 MHz. Accordingly, if a UE employs both radio technologies (BT and LTE), simultaneous interference may occur. As used throughout this disclosure, this interference among co-located transceivers in a UE is referred to as in-device coexistence (IDC) interference.
There is an ongoing study item in Radio Access Network 2 (RAN2) which is exploring possible solutions to IDC interference. See. 3GPP TR 36.816 V11.2.0 Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Study on Signaling and Procedure for Interference Avoidance for In-Device Coexistence, December 2011 Technical Report. Among the significant usage scenarios examined by the RAN 2 study are: (1) interoperability of LTE voice over IP (VoLTE) via a LTE transceiver where the voice traffic is transmitted and received by a BT transceiver deployed in an earphone or BT headset (VoIP service); and (2) interoperability of a LTE transceiver in a scenario where multimedia (for example a high-definition (HD) video) is downloaded by the LTE receiver and the audio is routed to a BT headset, and where the traffic activity between the LTE and the BT are correlated. It is noted that a transmission latency of more than 60 ms can cause audio playback problems at the BT receiver.
Among the promising, but not yet realized solutions for IDC interference have focused on radio resource control (RRC) signal manipulation undertaken by the UE in the RRC_CONNECTED state employing a time division multiplexing (TDM) solution. Two possible methods of accomplishing this TDM approach have been suggested: a discontinuous reception (DRX) approach, and a measurement gap (MG) approach. Each approach suggests muting or limiting the duration of LTE transmissions to give another in-device RAT access to the ISM frequency spectrum.
The DRX approach exploits DRX's functionality which can define a period of reduced power consumption of the UE. That is, the UE checks the downlink channel periodically so as to wake up only when downlink traffic is detected, but remains in the sleep mode state when no downlink traffic is detected. As such, the UE can apply DRX to essentially “switch off” its LTE receiver in order to preserve battery power.
In LTE there is a relationship between DRX functionality and the two possible RRC states in the UE. That is, different DRX functionality applies to UEs which are in RRC_CONNECTION state as opposed to RRC_IDLE state. Importantly, when in RRC_CONNECTED state, the UE does not need to monitor the downlink channels. DRX functionality includes DRX cycles which consist of an ‘On Duration’ during which the UE should monitor the packet data control channel (PDCCH), and a “DRX period” during which a UE can skip reception of downlink channels for battery saving purposes. These designations of the DRX cycles involves a trade-off between battery saving and latency. On the one hand, a long DRX period can be beneficial (i.e. in that it helps preserve the battery) On the other hand, a shorter DRX period provides for a faster response when data transfer is resumed.
To respond to these conflicting goals, LTE provides two DRX cycles, a short cycle and a long cycle, which can be configured for each UE in order to promote power saving in both the RRC_CONNECTED and RRC_IDLE states. The transition between a short DRX cycle, a long DRX cycle, and continuous reception is controlled by a DRX timer in the TIE.
The MG approach exploits known inter-frequency measurements (e.g., cell identification) performed during periodic measurement gaps (“idle gaps”) where the UE does not receive any download data. However, if the UE has more than one receiver it can receive on the alternative receiver. That is, two possible gap patterns can be configured by the network which are always 6 ms long in downlink (DL) situations and 7 ms long in uplink (UL) situations with a periodicity of 40 ms or 80 ms, respectively. For IDC purpose, shorter new gap patterns may be designed, and the new gap pattern may be called “IDC gaps”. Throughout this document, we still use measurement gap to keep it general, but it mainly refers to IDC gaps. Like DRX, there is a trade-off between gap patterns such as shorter or longer cell identification delay versus a greater or lesser interruption in data transmission and reception.
As mentioned above, the RAN 2 study focused upon a TDM solution which avoids transmission latency in the BT transceiver (<60 ms) in order to avoid the audio playback problem in a BT headset as described above. As shown in FIG. 2, TDM solutions (200) can be configured such that they have a scheduled period (220) and an unscheduled period (230) which do not exceed 60 ms and have a pattern periodicity (210) of 120 ms.
The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:                3GPP third generation partnership project        AP access point        BT Bluetooth™        CE control element        CIDS coexistence information and discovery server        DL downlink        DL-SCH downlink shared channel        DP data processor        DRX discontinuous reception        eNodeB base station of an LTE/LTE-A system        eSCO extended synchronous connection oriented        EUTRAN evolved UMT terrestrial radio access network,        FDM frequency division multiplexing        GSM global system for mobile communications        GNSS global navigation satellite system        GP gap pattern        GPS global positioning system        HSPA high speed packet access.        ID identifier        IDC in-device coexistence        IP internet protocol        ISM industrial, scientific and medical        LCID logical channel ID field        LTE long term evolution (of the evolved UTRAN system)        LTE-A long term evolution-advanced        MAC medium access control        MG measurement gap        PUCCH physical uplink control channel        SCO synchronous connection oriented link        TDD time division duplex        TDM time division multiplexing        RAN radio access network        RAT radio access technologies        RRC radio resource control        UE user equipment        UL uplink        UMT universal mobile telecommunications        UTRAN universal terrestrial radio access network        WCDMA wideband code division multiple access        WLAN wireless local area network        